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JFR Settings Files

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Use Java Flight Recorder (JFR) setting files (.jfc) to specify the event and control configuration. Check the JFR Command Line Options to understand how such a setting file can be used.

For instance, to change the settings file for a running recording:

jcmd <PID> JFR.config settings=my-config.jfc

Provided Settings Files

By default, Flight Recorder uses the settings defined in <java_home>/lib/jfr/default.jfc which gives a good balance between data and performance. In the same directory, you can find a second configuration profile.jfc which records more events and is useful while profiling an application.

You can also create a copy of one these files and create your own configuration, e.g. my-config.jfc.

Generating a Custom Settings File

As of JDK 19, it’s strongly encouraged to use the jfr configure utility to create a custom settings file.

$ jfr configure --interactive ============== .jfc Configuration Wizard ============ This wizard will generate a JFR configuration file by asking 12 questions. Press ENTER to use the default value, or type Q to abort the wizard. Garbage Collector: Normal (default) 1. Off 2. Normal 3. Detailed 4. High, incl. TLABs/PLABs (may cause many events) 5. All, incl. Heap Statistics (may cause long GCs) ...